Blood
Flow
Summary
Blood
Vessels
The Blood
The
Heart

The Circulatory System

Circulatory System Consists of…

Blood Vessels

Blood

Heart





The Heart pumps blood through the body through blood vessels
(arteries, capillaries and
veins)
Arteries take blood away from the heart, veins return blood to the heart
Blood carries O and CO
2 tissues
2
(food) towards
(waste) away from
The lungs are not part of the circulatory system!!


Pulmonary Circulation
– Carries blood to lungs and back

Systemic Circulation
– Carries blood to body and back

Your Blood Vessels:
Pathway of Circulation

3 types of vessels
– Arteries (mostly shown as Red because blood has O
2
)
– Capillaries (Red and
Blue because some O
2 lost to tissues)
– Veins (mostly shown as Blue because O
2 lost to tissues)


Blood is never blue!!!!!!!!!!!!!!!!!!

Oxygenated blood is bright red and deoxygenated blood is dark red

Veins appear blue because of the way light reflects off the blood vessel

We don’t see arteries because they are too deep.

We draw them blue to distinguish them on diagrams and simplify things

What you need to know about the STRUCTURAL differences between Arteries and Veins:
- Artery walls are much thicker, are very elastic and have more muscle
- Veins are thin walled and contain valves to push the blood along


Why are arteries and veins the way they are?
– Blood is under very high pressure when it leaves the heart and enters the arteries
 Therefore, arteries need to be
strong!!
– Once it has left the tissues and enters the veins, the blood is under a very low pressure
 Therefore, veins are weak

Arteries:
Carry blood A way from heart
– Large
– Thick-walled, Muscular
– Elastic
– Oxygenated blood
 Exception Pulmonary Artery
– Carried under great pressure
– Steady pulsating (used to measure pulse)
Arterioles: smaller vessels, enter tissue

– Smallest vessel
– Microscopic
– Walls one cell thick
– Located at the tissue
– Nutrients and gases
(O
2
, CO here
2
) diffuse

Veins:
Carry blood to the heart
– Carries blood that contains waste and CO
2
 Exception pulmonary vein
– Blood under low pressure
– Valves to prevent back flow due to gravity
Venules: small veins, larger than capillaries
Mechanism of Vein and Varicose Veins Videos

Animation of blood flow

The Aorta – The largest blood vessel
Blood Vessel Animation

Blood flow is like a round trip to grandma’s house
-
-
-
-
-
-
-
-
-
- You leave your home (The Heart)
You jump on the Highway (Arteries)
You get off at grandma’s street (Arterioles)
You pull in to grandma’s driveway (capillaries)
You go inside her house (The Cell) and give her a kiss
(Glucose and Oxygen)
You leave with leftovers (CO
2
)
Get back into your car and exit driveway (capillaries)
You drive back along her street (Venuoles)
You get back on the highway (Veins)
Arrive back at home (The Heart)



Body contains 4-6 L
Consists of
– Water
– Red Blood Cells
– Plasma
– White blood cells and platelets

Liquid Portion Carries
 Blood cells (made in bone marrow)
– Erythrocytes (RBC - red blood cells)
– Leucocytes (WBC - white blood cells)
 Platelets (fragments of the cells in bone marrow – no nucleus)
 Proteins
 Nutrients - Digestive System
 Gases - Respiratory System


Hemoglobin, iron containing molecule – found in RBC

Loosely picks up oxygen in the lungs

Releases oxygen in areas low in oxygen – body tissues
O
2
O
2
O
2
O
2


Hemoglobin also carries CO
2

CO
2 is a waste product of cellular respiration

Travels to the lungs to be exhaled


50% Water

45% Erythrocytes (RBC)

4% Plasma with Substances

1% Leukocytes (WBC) + Platelets






Transporters of
– Oxygen
– Carbon Dioxide
RBC
– Lack a nucleus
– Contain hemoglobin
– Disk-shaped
RBC are produced in the bone marrow
Lives for ~120 days
Old RBC are destroyed in liver and spleen







WBC fight infection
– Attack foreign substances
Less abundant
Created in the bone marrow
Some live for months
– Most just a few days
Several types
ALL contain nuclei


PLATELETS are for
CLOTTING blood

Cell fragments

Produced in bone marrow

Short life span (1 week)

Form a web trapping blood cells

Blood Clotting
Break in Capillary Wall
Blood vessels injured.
Clumping of Platelets
Platelets clump at the site and release a protein
Clot Forms
Protein creates a net creating a clot. The clot prevents further loss of blood.

Heart Anatomy


Pumps blood around your body to keep you alive!

If your heart stops you will die!

Heart:
Structure and Function

Keeps blood moving

Large organ composed of
– cardiac muscle
– rich in mitochondria

The Structures of the Heart
Vena Cava
Vein that brings oxygen-poor blood from the body to the heart
Aorta
– Artery that supplies the body with Oxygen-Rich Blood
Gets Oxygen-
Rich blood from the Lungs
Pulmonary
Arteries
Sends Oxygen-
Poor blood to the
Lungs
Pulmonary Arteries
Bring oxygen-poor blood to the lungs
Pulmonary
Veins
Bring oxygenrich blood from the lungs to the left atrium
Receives
Oxygen-
Poor blood from the body
Sends Oxygen-
Rich blood to the body
Sends
Oxygen-Poor blood to the lungs


Four chambers
– Two upper (Atria)
 Walls thinner
 Less muscular
– Two lower
(Ventricles)
 Walls thicker
 More muscular
 Do more work
Heart Structure Animation


Both Atria fill at same time
– Right atrium receives oxygen POOR blood from body from vena cavas
– Left atrium receives oxygen RICH blood from lungs through four pulmonary veins

After filled with blood atria contract, pushing blood into ventricle

Right ventricle contracts and pushes oxygen-poor blood toward lungs
 through the pulmonary arteries

Bloods Path Through the Heart
Left ventricle contracts and forces oxygen rich blood out of heart
 Through the aorta (largest vessel)

Animation of blood flow

Control of the Heart

The Heart is controlled by nerves and hormones:
Nerves:
– Its own nerves  pacemaker which keeps a constant beat
 Heart will beat even if it is disconnected from the brain
 Can be substituted by an artificial pacemaker
- The Brain  can speed-up (exercise) or slow down the heart (sleep) if needed


Heart Rate Animation

ECG and (Defibrillation) Paddles discussion

Hormones:

Certain hormones such as epinephrine
(adrenalin) impact how the heart operates
Heart Beat

Resting Heart Rate
(beats per min.)
Heart Rate during exercise
(beats per min.)


At REST, the heart beats about 60-80 times per minute
(~4.7L)

During EXTREME
EXERTION (exercise) it can beat between
150-200 times per minute (~38L)


Why??

Brain sends a signal to increase HR

Adrenal Gland secretes epinephrine

Both work together to increase blood flow around the body
– Increased blood flow = Increase O
2 delivery to cells and CO
2 removal
/glucose


Coronary Artery Disease
– Your heart needs Oxygen too!
– Is supplied with Oxygen by coronary arteries
– Coronary arteries can become partially blocked by plaque (fat and cholesterol mainly)
 Causes by lifestyle choice and genetics
– This block limits the amount of oxygen delivered to the heart
– Can cause  tiredness, dizziness and pain



Can be diagnosed with an angiogram whereby a fluorescent dye is injected into the bloodstream.
This dye shows up on an x-ray and shows where flow is disrupted


Heart Attack
– Coronary Artery(ies) become completely blocked
 No Oxygen can reach the heart muscle
 Heart muscle begins to die and eventually stops beating
 Symptoms
– Nausea, Shortness of breath, Severe chest pain, sweating, dizziness, fatigue
IMMEDIATE MEDICAL ATTENTION NECESSARY
Heart Attack 1 Heart Attack 2


Stroke
– Heart attack for the brain
– Blood cannot reach the brain due to a blockage in its blood vessels or severe brain bleed.
– Brain cells die due to lack of oxygen
– Can lead to paralysis,
 loss of ability to speak
 death
Causes a Stroke?

Current PREVENTION
Recommendations

Regular exercise

Weight control

Well balanced diet

Do not smoke

Diet low in saturated fat

Bill Nye – Blood and Circulation Video
Download the Blood and Circulation
Worksheet